The present invention relates to a numeral display device adapted for use for example in an electronic desk-top calculator, and more particularly to a numeral display device capable of displaying numerals in multiple rows and to a numeral display device capable of providing a display with elevated contrast and with a simplified drive circuit.
2. Description of the Prior Art
The various display devices known in the prior art have inevitably been associated with the following drawbacks:
(1) They are unable to display numerals with decimal points in multiple rows with a simple construction: PA1 (2) The conventional display devices, if simply constructed for the display of two rows, will result in a reduced display contrast due to the increased resistance of prolonged transparent leads: PA1 (3) A display device for multiple-row display inevitably requires considerably complicated connections with an area necessary for the electric leads, which renders the compact arrangement of the upper and lower rows impossible: PA1 (4) In the dynamic display method, a display device for a row of six digits for example usually employs a drive method with a duty time of 1/6, but the subdivision of drive time for each digit by a half employed in recent technology leads to a duty time of 1/12 with an accordingly further reduced contrast of display: PA1 (5) Such method, requiring 12 electrodes in the above case, namely twice as many as the number of digits, becomes more unfavorable as the number of digits increases: PA1 (6) The neighboring electrodes, if derived to a same direction, will be located excessively dense, will not be able to have enough respective areas and will pose difficulty in making connections with the external leads. PA1 (7) In the dynamic display scheme, if the driving time interval for the segments forming the figure eight digits is not uniform, contrast of the display will not be uniform. Thus it is necessary to provide a uniform driving time interval for each segment.